1. Field of the Invention
The present invention relates to a paper fastener, and more particularly to a paper fastener having side flanges folded and shielded for preventing the burred side flanges of the paper fastener from hurting users.
2. Description of the Prior Art
U.S. Pat. No. 6,217,246 to Yu discloses one of the typical paper fasteners. FIG. 1 shows the cross sectional view of Yu""s paper fastener which includes a base 20 having two folded side flanges 21 and having two end prongs 22, a compressor 10 having two holes for receiving the prongs 22 and also having two folded side flanges 12, and two retainers slidably engaged onto the compressor 10 for engaging with the folded prongs 22 and for detachably securing the compressor 10 and the base 20 together. However, the compressor 110 and the base 20 are normally made by punching processes, such that the folded side flanges 12, 21 of the compressor 10 and the base 20 may be rough or serrated or burred. In addition, the compressor 10 and the base 20 have not been suitably shielded or covered, such that the compressor 10 and the base 20 may easily hurt the users.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional paper fasteners.
The primary objective of the present invention is to provide a paper fastener including folded side flanges that may be shielded for preventing the burred side flanges of the paper fastener from hurting users.
In accordance with one aspect of the invention, there is provided a paper fastener comprising a base including two ends each having a leg extended therefrom and foldable relative to the base for engaging through sheet materials, the base including two side panels bent relative to the base for forming a bent portion between the side panels.and the base respectively, the side panels being located lower than the base for forming a recess between the base and the side panels respectively, the side panels each including an outer flange folded relative to the side panels respectively and engaged into the recess of the base and engaged with the side panels respectively, the outer flanges of the side panels each including a free edge located beside the bent portions of the base and shielded by the bent portions and the side panels of the base respectively, a bar including two end orifices for receiving the legs of the base and for engaging onto the sheet materials, the legs of the base being foldable to engage onto the bar for clamping the sheet materials between the base and the bar, the bar including two side flaps bent relative to the bar for forming a bent portion between the side flaps and the bar respectively, the side flaps being located higher than the bar for forming a recess between the bar and the side flaps respectively, the side flaps each including an outer flange folded relative to the side flaps respectively and engaged into the recesses of the bar and engaged with the side flaps respectively, the outer flanges of the side flaps each including a free edge located beside the bent portions and shielded by the bent portions and the side flaps of the bar, and two retainers slidably engaged on the bar for engaging with the legs and for securing the paper sheets between the base and the bar.